The idea here is to set up a point on the MM jig
that corresponds to the center of the prop flange
in the cowl hole.

Run a string back through the center hole on Jeff's
motor mount plate to the firewall. The angle of
the string relative to the horizontal will be the
down thrust angle if any. You will have to adjust
the plate up and down to get the hole in the center
of the string. You will then have to tilt the plate
forward at the down thrust angle.

You will also have to rotate the
front movable part of the jig around the pivot
point to set the side offset angle.

The information you will need to build a motor mount
from a kit plane is the position of the hole in the
cowl relative to the firewall. Unfortunately
this information is not given on the plans so you
will have to measure it. Here is a JPG that shows
how to do that.

If you are building your own cowl some of these steps
can be avoided as you will fit the cowl to the installed
engine.

You will also need the down thrust angle if any and
the offset angle if any.

With that info you can set up a jig to build an
accurate motor mount that will result in the prop
flange coming out in the center of the cowl hole.

Hopefully someone will build  a jig  and offer to
build motor mounts saving you the time.

Paul Lamar

Paul,

I  have been off line for a while due to computer issues, but I did offer
to build a jig about a month back. I asked at that time about building in
offsets. I am more or less ready to go building a jig and it could be ready
by the time I could get the tubing here. My design (pen and paper style)
differs from yours somewhat. My simulated firewall is the base lying
horizontal and the mount is built projecting upward. A beam/plate simulator
is mounted to the firewall and holds the mount cups in the correct relative
positions.

Three threaded rods allow the beam/plate simulator to adjust
up/down and side thrust angles as well as fine tune the distance from the
firewall. I was going to make a mount for the STOL King but there were some
size issues or questions (emails lost in the puter issues and my own RAM
useless). The only reason I haven't gone ahead is so far no one seems
interested in having a mount made.

If it results in a mount or two a year
that is fine, I would certainly build a mount for that, the cost and labour
to do that is not significant and it would make building different mounts
very simple. Of course for a hombuilder to skadge together a one time jig
with universality to build many differing mounts is pretty simple too. I
certainly don't anticipate surpassing BG in the Forbes 500 list with this
but it would complement other production projects that I am working on.

These other items are mostly outside the experimental market (due to market
size) but the front burner project is the building of a CNC table, which
will be capable of plasma cutting all of the fittings for various plans
built a/c etc.

John

Well if you have some sketches perhaps you can scan them and send
them to us. Lacking that make a copy and mail it to me and I can
scan it.

Paul Lamar
830 East Santa Maria St
Suite 303 Very very Important.
Santa Paula CA
93060


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